Reply With QuoteThere are good reasons to not do it that way. Exercise for the reader as to what those are
Hey all,
So this is related to my earlier thread asking for a G4 valve...
Basically, I decided that it might be fun to draw up an increasing force PCP responsive to breech pressure - basically a Lurker Control Freak poppet, but actuated with air instead of a ram.
Anyways, I don't have the R1 of the CAD done, but here are some in progress shots - I grabbed the Ego valve off ZDSPB and started with that. I need to develop the rocket cap still.
In an attempt to spec out a spring, I kind of realized that I don't know the kind of back pressure that the valve would be seeing, and since this is a necessary item, I figured I'd turn to the masters here.
Does anyone have any information that can lead me in the right direction, or any thoughts? I may be in way over my head, and if that happens... oops.
Thanks guys,
Brandon
There are good reasons to not do it that way. Exercise for the reader as to what those are
Do you mean the overall concept, or a certain part in particular?
The overall concept I could see timing and valve bouncing open and shut being an issue with overdwelling. I'm sure there are others.
Pretty much. You can't really count on a transient force to fight the ram force, it's too timing fiddly.
Unless I'm missing something I don't think he's going to have the ram interact with the poppet at all.
Ever so many citizens of this republic think they ought to believe that the Universe is a monarchy, and therefore they are always at odds with the republic. -Alan Watts
I work for the company building the Paragon
I should have mentioned, the idea is that this is for a stacked closed bolt system. Without serious tuning to the counterbore/vent thing, it wouldn't work for a blow forward.
I guess I could've shown the valve housing from multiple angles and not just wire frame too... will post that later. Along with a slightly revised version - it's just more compact.
The valve is supposed to be (my concept) a G4 Control Freak poppet, but air actuated instead of a ram.
Last edited by new ion?; 09-08-2014 at 12:35 AM.
So it will have the same function as an mQ valve? Except this valve opens on pneumatic input vs. electronic input. What you could do to solve the valve bouncing issue is put higher pressure into the piston chamber. I think the only way to stop the valve from bouncing is to have the opening force larger than the closing force at any point in the cycle.
I think he just means valve opening force in general.Originally Posted by PBSteve
I don't know, fly casual
No, the issue is that the back pressure closing the valve is only present for so long. It's not a constant force. Once that dissipates, if there's pressure still at the head of the poppet, the valve will open again.
Another issue with, well, my knowledge is stiction - I can adjust the shifting forces on this poppet to be down to like 4lbs (excluding spring, haven't specced that yet) but I'm unsure if it would be reliable at that low of an opening force. There's going to be 2 dynamic seals. Of course this would be dependent on oring crush..
edit - from what I can understand, this system would be similar to a GSL without the ISCIS valve.
Last edited by new ion?; 09-08-2014 at 02:09 AM.
What you could do is have the valve vent the actuating force at full throw, like I do in the Shocker/Luxe Eigenbolt. But, it's still going to be dwell-critical with respect to oscillation. Which might be fine for a one off, but I doubt suitability for production.
The GSL is pressure latching as per the GEO2 and merely uses the breech pressure to assist in the dynamics - the latching state is pre-determined by the balance of spring and pressure acting on faces (hint)
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